1. Field of the Invention
The present invention relates to an image processing apparatus for controlling copy operation by embedding information for copy inhibition or information for tracing print-out operations, and by extracting the information thus embedded.
2. Description of the Related Art
With the development of IT technology in offices, there has been an increasing concern for security in recent years. For example, cases of leakage of corporate customer information have frequently occurred, and such threatening of personal privacy has become a great social problem.
To deal with such problems, measures for preventing information leakage to the outside of a firm have been taken in general, for example, by controlling an access right to digitized confidential information and by installing a monitoring device for a firewall. Moreover, there is a measure in which portable media such as a notebook computer or a USB memory are forbidden to be carried into and out of an office. In the case of digitized confidential information, corporate customer information can be protected by determining and implementing monitoring policies, as described above. However, when confidential information is printed on a paper medium with a printer, it is considered to be more difficult to check or forbid the carrying-out of the paper medium on which personal information is printed, than to restrict the carrying-out of digitized confidential information. This makes it difficult to maintain security.
To ensure security of printed material, there is a copy restriction technology (e.g., Japanese Patent Laid-open No. 2003-280469) in which information on copy permission or copy inhibition of a printed material under a particular condition is embedded in an original document in the form of a dot pattern or a bar code so that copy is restricted. Further, there is a tracking technology (e.g., Japanese Patent Laid-open No. 2003-205661) for tracking persons who make copies. In this technology, copy inhibit information and information indicating a place where copy history information is embedded are embedded into a digital watermark of a type embedded into the entire surface of a sheet of paper.
In the tracking technology of Japanese Patent Laid-open No. 2003-205661, in addition to a digital watermark, an editable bar code and image position information of the bar code are embedded into the digital watermark. At the time of copying, the image position of the bar code is identified from extracted digital watermark information, and it is determined whether the bar code is embedded at that position. In this technology, when the bar code is not embedded at that position, copying is prohibited as a fraudulent copy.
However, in the above-described conventional technologies, there is a problem that an embedding area of copy history information is fixed at the first print, and may eventually run out of its information capacity as copies are repeatedly made.
Meanwhile, as to the above-described problems, the shortage of the information capacity of the embedding area of copy history information can be avoided by adding an embedding area of copy history information at the time of copying. However, it is not possible to detect a falsification of the embedding area of copy history information without determining, for each copy, how the embedding area has been added. To manage copy generation information for paper copies, it is necessary to prevent copy history information from being falsified.
In a copy generation management technique using paper in particular, the present invention aims to enable falsification detection in which a falsification is determined as being made if pieces of embedded information fail to be extracted in order of copy generation, and also to increase the capacity of embedded information while maintaining security.
An aspect of an image processing device of the present invention is that the image processing device comprises: deleting means for deleting additional information from document image data in which the additional information is embedded, the additional information (called embedding-end information below) indicating the end of embedding additional information; and embedding means for embedding second information into an area where the embedding-end information is deleted by the deleting means, the second information (called additional-information presence information below) indicating the presence of other additional information newly added.
In accordance with the above aspect, the image processing device of the present invention is characterized in that the embedding means further embeds third information at a position different from a position where the additional-information presence information is embedded, the third information being different from the embedding-end information and the additional-information presence information.
In accordance with the above aspect, the image processing device of the present invention is characterized in that the embedding means embeds third information at a position indicated by the additional-information presence information, the third information being different from the embedding-end information and the additional-information presence information.
In accordance with the above aspect, the image processing device of the present invention is characterized in that the embedding-end information and the third information are information respectively indicating that areas where the embedding-end information and the third information are respectively embedded are areas where latest information is embedded.
In accordance with the above aspect, the image processing device of the present invention is characterized in that the document image data includes background embedded information, the background embedded information is information in which predetermined information is repeated; and not all of the background embedded information is deleted even when part of the background embedded information is deleted due to the embedding of information performed by the embedding means.
In accordance with the above aspect, the image processing device of the present invention is characterized in that the background embedded information includes positional information indicating a position for firstly embedding information including copy history information on copy history of an original document.
An aspect of an image processing method of the present invention comprises: an embedding step of embedding additional-information presence information into document image data in which embedding-end information is embedded. The image processing method characterized in that the embedding step includes: deleting the embedding-end information from the document image data; and embedding the additional-information presence information in an area where the embedding-end information is deleted.
In accordance with the above aspect, the image processing method is characterized in that, the embedding step includes embedding third information at a position different from a position where the additional-information presence information is embedded, the third information being different from the embedding-end information and the additional-information presence information.
In accordance with the above aspect, the image processing method is characterized in that, the embedding step includes embedding third information at a position indicated by the additional-information presence information, the third information being different from the embedding-end information and the additional-information presence information.
In accordance with the above aspect, the image processing method is characterized in that, the embedding-end information, and the third information is information indicating that an area in which either of the embedding-end information and the third information are embedded is the area in which latest information is embedded.
In accordance with the above aspect, the image processing method is characterized in that, the document image data includes background embedded information, the background embedded information being information in which predetermined information is repeated; and not all the background embedded information is deleted even when part of the background embedded information is deleted due to the embedding of information performed in the embedding step.
In accordance with the above aspect, the image processing method is characterized in that, the background embedded information includes positional information indicating a position for firstly embedding information including copy history information on copy history of an original document is first embedded.
The respective steps of the above image processing method may be configured as a program for causing a computer to perform the step, the program being provided to a computer of an image processing device or to an information processing system. By causing the computer to read this program, the image processing method is performed by the computer. Further, the computer may read this program via a computer readable storage medium storing the program.
An aspect of an image processing device of the present invention is that the image processing device includes:                deleting means for deleting an image of an area in which additional-information presence information is not embedded and in which additional information different from the additional-information presence information is embedded; and        
embedding means for embedding additional-information presence information into the area in which the image is deleted by the deleting means.
An aspect of an image processing device of the present invention is that the image processing device includes: deleting means for deleting embedding-end information from document image data in which the embedding-end information is embedded; and embedding means for embedding additional-information presence information into an area in which the embedding-end information is deleted by the deleting means, the additional-information presence information being different from the embedding-end information.
In this specification, the image processing device is assumed to include a general purpose information processing device capable of performing processes related to the present invention, in addition to a dedicated image processing device and a dedicated image forming device.
In accordance with the present invention, even when there are plural areas each embedded with information, information for tracking embedded positions in sequence is embedded into each of the areas, whereby all the embedding areas can be identified. Thus, in a copy generation management using paper in particular, it is determined that a falsification has been made unless all embedded pieces of information (copy history information, in particular) are extracted in order of copy generation, and also capacity extension of embedded information is achieved, while maintaining security.
Further features of the present invention will become apparent from the following description of exemplary embodiments (with reference to the attached drawings).